The present application relates to an illumination unit that includes a light modulation device that exhibits scattering characteristics or transparency with respect to light, and also relates to a display.
Recently, high image quality and energy saving in liquid crystal displays have been radically proceeded and there is proposed a scheme that achieves improvement in contrast in a dark place by partially modulating light intensity of a backlight. In this technique, mainly, a light emitting diode (LED) used as a light source of the backlight is partially driven to modulate light from the backlight in accordance to a display image. Also, a demand for reducing thickness has been increased in a large liquid crystal display as in a small liquid crystal display. Therefore, attention has been attracted not to a scheme that arranges, for example, a cold cathode fluorescent lamp (CCFL), an LED, or the like directly beneath the liquid crystal panel, but to an edge-light scheme that arranges a light source at an end of a light guide plate.
The present applicant has achieved partial drive that partially modulates light intensity of the light from the backlight in the edge-light scheme, and has disclosed the technique, for example, in Japanese Unexamined Patent Application Publication No. 2011-142065 (JP 2011-142065A). In JP 2011-142065A, a polymer dispersed liquid crystal (PDLC) is used in order to achieve the above-described partial drive. In JP 2011-142065A, the PDLC is formed by mixing a liquid crystal material and a low-molecular material with alignment properties and polimerizability and by causing phase-separation by ultraviolet irradiation, and the PDLC is a composite layer in which the liquid crystal material is dispersed in a polymer material having a streaky structure. The PDLC is classified into a horizontal alignment type, a vertical alignment type, and an isotropic type, depending on alignment upon no voltage application. Out of the foregoing types, the horizontal alignment type achieves high luminance and high contrast, and therefore, is most suitable for a backlight.